Extension of life-span by introduction of telomerase into normal human cells.
Normal human cells undergo a finite number of cell divisions and ultimately enter a nondividing state called replicative senescence. It has been proposed that telomere shortening is the molecular clock that triggers senescence. To test this hypothesis, two telomerase-negative normal human cell types, retinal pigment epithelial cells and foreskin fibroblasts, were transfected with vectors encoding the human telomerase catalytic subunit. In contrast to telomerase-negative control clones, which exhibited telomere shortening and senescence, telomerase-expressing clones had elongated telomeres, divided vigorously, and showed reduced straining for beta-galactosidase, a biomarker for senescence. Notably, the telomerase-expressing clones have a normal karyotype and have already exceeded their normal life-span by at least 20 doublings, thus establishing a causal relationship between telomere shortening and in vitro cellular senescence. The ability to maintain normal human cells in a phenotypically youthful state could have important applications in research and medicine.
Bodnar
A G
AG
Geron Corporation, Menlo Park, CA 94025, USA.
Ouellette
M
M
Frolkis
M
M
Holt
S E
SE
Chiu
C P
CP
Morin
G B
GB
Harley
C B
CB
Shay
J W
JW
Lichtsteiner
S
S
Wright
W E
WE
D015415:Biomarkers; D002384:Catalysis; D002455:Cell Division; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D016922:Cellular Senescence; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins; D005347:Fibroblasts / Q000166:cytology; D006706:Homeostasis; D006801:Humans; D007621:Karyotyping; D010641:Phenotype; D010857:Pigment Epithelium of Eye / Q000166:cytology; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D012313:RNA; D012194:RNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology / Q000201:enzymology; D019098:Telomerase / Q000235:genetics / Q000378:metabolism*; D016615:Telomere / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D014162:Transfection; D014407:Tumor Cells, Cultured; D001616:beta-Galactosidase / Q000378:metabolism
D015415:Biomarkers; D004268:DNA-Binding Proteins; D011506:Proteins; C422952:telomerase RNA; D012313:RNA; D012194:RNA-Directed DNA Polymerase; D019098:Telomerase; D001616:beta-Galactosidase